From my experience, the ex Eastern Bloc countries. I am speaking about all the STEM fields, not just SWE. I remember that my mom (Romanian) was shocked when I told her that in my CS high school class (in Italy) we were all boys.
That's interesting. I'm half Polish and I know that there is a perspective that women do really well in science/STEM, but I don't think I've seen them participate at equal rates as men. And when I talk to tech companies in Poland these days, they say their engineering teams are predominantly male and they'd like to change that (which is one reason they want to partner with Manara!)
EDITED: Also, when I worked at Upwork as a PM, most of our software engineers were from Eastern Europe (Russia, Ukraine, Belarus, etc) and we had almost no women on the team.
India, Israel, Russia basically anything that is not "west" but has some tech culture. They are still a minority but seems to do better. This is just my impression not some study but I think it is actually true. I am a bit sarcastic there and I got some ideas why it happens like that but serious discussion is useless since it became a political issue rather than something you can discuss openly, hence the sarcasm.